Loki: Default to /labels API with query param instead of /series API (#97935)

* feat(loki-labels-api): add feature toggle

* feat(loki-labels-api): default to `/labels` API

pkg/services/featuremgmt/registry.go

@@ -1689,6 +1689,13 @@ var (
 			Owner:        grafanaFrontendPlatformSquad,
 			FrontendOnly: true,
 		},
+		{
+			Name:        "lokiLabelNamesQueryApi",
+			Description: "Defaults to using the Loki `/labels` API instead of `/series`",
+			Stage:       FeatureStageGeneralAvailability,
+			Owner:       grafanaObservabilityLogsSquad,
+			Expression:  "true",
+		},
 	}
 )
 

pkg/services/featuremgmt/toggles_gen.csv

@@ -225,3 +225,4 @@ alertingNotificationsStepMode,experimental,@grafana/alerting-squad,false,false,t
 feedbackButton,experimental,@grafana/grafana-operator-experience-squad,false,false,false
 elasticsearchCrossClusterSearch,preview,@grafana/aws-datasources,false,false,false
 unifiedHistory,experimental,@grafana/grafana-frontend-platform,false,false,true
+lokiLabelNamesQueryApi,GA,@grafana/observability-logs,false,false,false

pkg/services/featuremgmt/toggles_gen.go

@@ -910,4 +910,8 @@ const (
 	// FlagUnifiedHistory
 	// Displays the navigation history so the user can navigate back to previous pages
 	FlagUnifiedHistory = "unifiedHistory"
+
+	// FlagLokiLabelNamesQueryApi
+	// Defaults to using the Loki `/labels` API instead of `/series`
+	FlagLokiLabelNamesQueryApi = "lokiLabelNamesQueryApi"
 )

pkg/services/featuremgmt/toggles_gen.json

@@ -2095,6 +2095,19 @@
         "codeowner": "@grafana/observability-logs"
       }
     },
+    {
+      "metadata": {
+        "name": "lokiLabelNamesQueryApi",
+        "resourceVersion": "1734096677730",
+        "creationTimestamp": "2024-12-13T13:31:17Z"
+      },
+      "spec": {
+        "description": "Defaults to using the Loki `/labels` API instead of `/series`",
+        "stage": "GA",
+        "codeowner": "@grafana/observability-logs",
+        "expression": "true"
+      }
+    },
     {
       "metadata": {
         "name": "lokiLogsDataplane",